It is always difficult to assemble micromachinable components to conventional mechanical components in timepiece mechanisms due to sensitivity to shear stress.
EP Patent 2755093 in the name of MASTER DYNAMIC discloses a balance spring collet for a press fit with the shoulder of a timepiece balance wheel, the collet comprising elastically deformable arms, forming an annular space and together delimiting an aperture, each arm comprising a curved concave engagement portion for engagement with such a shoulder, all of the same radius of curvature and equidistant from the central axis, in the free state at a first distance, less than the radius of the shoulder. These engagement portions have a radius of curvature such that, upon deformation of the arm portions, and engagement with the outer surface of the shoulder, the engagement portions substantially conform with the outer surface of the shoulder, and the press fit induced stresses are transferred to and distributed in the arms, so as to prevent any relative movement between the collet and the shoulder upon application of a return force from the balance spring.
EP Patent Application 2743782 A1 in the name of NIVAROX-FAR SA discloses, for timepiece components, a system of assembling a member made of a first material in the aperture of a part made of a second material having no plastic range, using an intermediate portion made of a third material, mounted between said member and said part. This part is received against a first level of the intermediate portion and is resiliently locked on a second level of the intermediate portion by the member in order to make integral the assembly of the member-intermediate portion-part.